In wireless devices in which an antenna-equipped wireless module is stored inside a casing, antenna characteristics sometimes deteriorate. In order to improve antenna characteristics, the following antennas are known. For example, a microstrip antenna that has a dielectric adhered to an antenna surface is known (for example, see PTL 1). Furthermore, an antenna device which has a radome that maintains a space in a constant manner between a radiation element and interior glass, which corresponds to a casing, is known (for example, see PTL 2).